XR-1 Racing Mufflers are the choice of today's hottest drag and oval track racers. With a patented straight-through design and multicore technology, XR-1 Mufflers actually outflowed a straight pipe in repeated testing. XR-1 Race Products are made of quality austenitic stainless steel for track-tough durability. They use sound-absorbing stainless steel packing to prevent burnout and meet the strictest noise requirements. Hands down, Borla's XR-1 Series offers the best balance of sound and power. Made in the USA!